# Effect Size Scaling

## Z₁ Variation

| Metric | Value |
|---|---|
| Total SD | 1.3651 |
| Within-country SD | 0.2699 |
| Between-country SD | 1.3409 |
| Average 20-year change | 0.2735 |

Note: The within-country SD (0.27) is the relevant scale for interpreting within-country effects. The average 20-year change is computed as the mean of rolling 20-year differences in Z₁ across all countries with sufficient data.

## Scaled Effects (Within-Country Interpretation)

| Dep Var | Z₁ Coef | 1 Within-SD (0.27) | 20-yr Aging (0.27) |
|---|---|---|---|
| National Savings | 90.2 | 24.3 pp | 24.7 pp |
| Private Saving | 60.0 | 16.2 pp | 16.4 pp |
| Govt Saving | 22.3 | 6.0 pp | 6.1 pp |

Coefficients are from Z → dep_var regressions (PanelGLS). Effects in percentage points of GDP. Cross-sectional IQR effects (spanning the full range from young to old countries) are mechanically very large and should not be interpreted as plausible country-level effects; the within-country scaling is the appropriate basis for policy interpretation.
